This invention relates to a valve assembly for a piston compressor, more particularly to a durable and highly efficient valve assembly for a piston compressor which has slidable valves.
Referring to FIGS. 1 and 2, a conventional valve assembly for a piston compressor interconnects a cylinder body 21 and a cylinder cover 22 and includes a generally disc-shaped valve seat member 11, an outer diaphragm 12, an inner diaphragm 13 and a positioning plate 14. The outer diaphragm 12 and the inner diaphragm 13 are flexible and are fastened to the center of the valve seat member 11. An inlet 111 and an outlet 112 are formed through the valve seat member 11. Normally, the inlet 111 and the outlet 112 are respectively closed by the inner diaphragm 13 and the outer diaphragm 12. The positioning plate 14 is also fastened to the center of the valve seat member 11, in such a manner that it presses the outer diaphragm 12 against the valve seat member 11. Because the positioning plate 14 has a curved portion, the outer diaphragm 12 can flex to open the outlet 112 of the valve seat member 11.
When the piston assembly 211 moves away from the valve assembly 11 in a suction stroke, gas outside the cylinder body 21 breaches the seal formed by the inner diaphragm 13 and enters the space between the valve assembly and the piston assembly 211. When the piston assembly 211 moves toward the valve assembly in a compression stroke, gas between the valve assembly and the piston assembly 211 is compressed so as to push and flex the outer diaphragm 12. This flexibility of the outer diaphragm 12 allows gas to be pushed out of the space between the valve assembly and the piston assembly 211. The diaphragms 12 and 13 easily incur elastic fatigue and have the disadvantages of unsatisfactory durability and sealing effects.